The 22-year-old - who spent last year on loan with Latics, helping them to the League One title - has undergone surgery and is set for an extended spell on the sidelines.
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“Was absolutely gutted to start pre-season getting injured out in Austria," Watts posted on social media. "But operation on my knee went well and back home smiling, ready to take each step on road back to playing.”
Latics have still not replaced Watts in their own squad, and manager Leam Richardson recently did nothing to hose down the suggestion he would be open to another season-long loan if it was possible.
"I think we're open to everyone and everything at the moment," he said. "Kell did great for us last year, he's a player who's learning the game and had a fantastic season here.
"He's a professional who'll definitely go on and have a great career."
Watts also admitted his year with Latics had given him the confidence to challenge for a place at Newcastle.
"I enjoyed my time at Wigan," he said. “Winning trophies is what I want to do.
"I’m a much more confident centre-half and going away to Wigan, getting that medal and getting that promotion, it’s something I will always remember.
“You can’t take that away from me, but I just want to kick on and see where that takes me.”